A novel impedance biosensor was developed based on the combination of a bio-nanobead separation/concentration procedure and an interdigitated array nanoeletrode and was demonstrated for sensitive and rapid detection of H5 subtype of avian influenza virus (AIV). Magnetic nanobeads with a diameter of 30 nm were coated with H5 subtype-specific monoclonal antibodies to selectively capture the target virus. An interdigitated array nanoeletrode was designed and fabricated for impedance measurement. Changes in the impedance of the antibody coated nanobead-virus complex was measured and correlated to the presence of H5 AIV (e.g., H5N1). The nanobead and nanoeletrode based impedance biosensor was able to detect AIV H5N1 at titer of 0.0128 HA unit/50 μl. Equivalent circuit analysis indicated that the solution resistance was responsible for the impedance change due to the presence of target virus.